Method of sulfonating mixtures of olefin and aromatic hydrocarbons

ABSTRACT

Improved processes for obtaining biodegradable detergents of good color using less sulfonating agents and minimizing or abolishing the requirement for decoloring; in which a mixture including ortho-dialkyl benzenes having linear alkyl radicals and linear olefin hydrocarbons (prepared by cyclization dehydration of normal paraffin stock having 14 to 24 carbon atoms) is sulfonated and neutralized twice with the organic phase from the first sulfonation forming the charge for the second. The efflux from at least the second neutralization is saponified and the aqueous phase of such saponification efflux yields the desired detergent. The first sulfonation is effected in the presence of a deficit of the sulfonating agent with respect to the sulfonatable hydrocarbons and the second with an excess.

United States Patent [1 1 Marty Apr.9, 1974 [75] Inventor: Claude Marty, Le Havre, France [73] Assignee: Compagnie Franc aise de Raffinage,

Paris, France [22] Filed: Nov. 23, 1971 [21] Appl. No.: 201,501

[30] Foreign Application Priority Data Nov. 24. 1970 France 70.42195 [52] US. Cl 252/556, 252/555, 252/558, 1 260/505 S [51] Int. Cl. ..Cl1d 11/04, C11d1/37 [58] Field of Search 260/505 A, 505 S, 513,

[56] References Cited UNITED STATES PATENTS 3,259,645 7/1966 Brooks et a1 260/459 3,346,505 10/1967 Blakeway et a1 252/558 3,361,797 1/1968 Bloch 260/505 A 3,409,637 11/1968 Eccles et a1 260/327 3,492,239 1/1970 Baumann et a1 252/551 3,681,442 8/1972 Bloch et a1 260/505 FOREIGN PATENTS OR APPLICATIONS 1,210,217 3/1960 France METHOD OF SULFONATING MIXTURES OF OLEFIN AND AROMATIC HYDROCARBONS 1,074,253 7/1967 Great Britain OTHER PUBLICATIONS Marquis et a1., Alpha-Olefin Sulfonates from a Commercial SO Air Reactor, JOACS, Vol. 44, Nov. 1966, pp. 607 & 608.

Primary Examiner-Herbert B. Guynn Assistant Examiner-P. E. Willis Attorney, Agent, or Firm-Curtis, Morris & Safford 5 7 ABSTRACT Improved processes for obtaining biodegradable detergents of good color using less sulfonating agents and minimizing or abolishing the requirement for decoloring; in which a mixture including ortho-dialkyl benzenes having linear alkyl radicals and linear olefin hydrocarbons (prepared by cyclization dehydration of normal paraffin stock having 14 to 24 carbon atoms) is sulfonated and neutralized twice with the organic phase from the first sulfonation forming the charge for the second. The efflux from at least the second neutralization is saponified and the aqueous phase of such saponification efflux yields the desired detergent. The first sulfonation is effected in the presence of a deficit of the sulfonating agent with respect to the sulfonatable hydrocarbons and the second with an excess.

12 Claims, No Drawings METHOD OF SULFONATING MIXTURES OF OLEFIN AND AROMATIC HYDROCARBONS The present invention relates to a method of obtaining compositions of sulfonates by sulfonation of mixtures of olefin and aromatic hydrocarbons. It also re lates to the alkaline sulfonates obtained by means of this process, as well as to the use of the said sulfonates as detergents.

It is known that the main constituents of the ordinary detergents marketed in the form of powders are alkaline sulfonates. These sulfonates are generally obtained by sulfonation of hydrocarbons and then neutralization of the sulfonic acids. The most generally used of these hydrocarbons are the alkyl benzenes. It has been shown that the structure of the alkyl radical determines the biodegradability of the resultant detergent, i.e., the ability of the detergent to be biologically degraded by microorganisms living in water. The presence of a single tertiary carbon in the alkyl radical is a cause of hardness of the detergent. The present trend is towards the obtaining of softer and softer .detergents. For this reason, alkyl benzenes whose alkyl radical is perfectly linear are being used more and more.

The applicant and his co-workers have shown that orthodialkyl benzene sulfonates having a total number of carbon atoms between 14 and 24 and entirely linear alkyl radicals constitute good detergents. Moreover, they are rapidly degraded by bacteria. During subsequent work, they have shown that the products resulting from the sulfonation of a mixture of aromatic hydrocarbons (whose principal components are orthodialkyl benzenes having linear alkyl radicals) and of linear olefin hydrocarbons constitute, after neutralization, very good biodegradable detergents. Reference is made to applicants earlier copending joint application, Ser. No. 115,488, filed Feb. 16, 1971 (French Appln. No. 7,005,438). See also applicants co-workers application Ser. No. 22,237, filed Mar. 24, 1970.

This simultaneous contacting of the sulfonating agent in excess with the mixture of aromatic and olefin hydrocarbons, the duration of which contacting must be sufficient for the sulfonation of the unsaturated hydrocarbons to take place, is accompanied by a secondary reaction on the olefins which leads to a harmful consumption of the sulfonating agent by attachment to the sultones formed and to a further production of sulfuric acid. Moreover, the products obtained are of relatively dark color, which frequently makes a decoloring treatment necessary.

An object of the present invention is to carry out a process of sulfonation of a mixture of olefin and aromatic hydrocarbons which avoids the above-described drawbacks.

To achieve this object, the applicant has evolved a process of sulfonation in stages, which does not require the prior separation of the components of the mixture and which can be applied to a mixture of hydrocarbons both with or without paraffins.

A preferred embodiment of the present invention is therefore a method of sulfonating a mixture containing olefin and aromatic hydrocarbons by the following successive steps:

a. A first sulfonation carried outwith a deficiency of the sulfonating agent relative to the sulfonatable hydrocarbons;

b. A first treatment by an alkaline base of the efflux from the first sulfonation;

c. A second sulfonation, carried out on the organic phase coming from the first treatment by an alkaline base, the said second sulfonation being carried out in the presence of an excess of sulfonating agent relative to the sulfonatable hydrocarbons present;

d. A second treatment by an alkaline base of the efflux from the second sulfonation.

In a specific embodiment of this method the respective treatments by an alkaline base of the efflux from both the first and second sulfonations consist of a neutralization at ordinary temperature, followed by a saponific'ation under autogenous pressure at a temperature of between C and 300C.

In a second specific embodiment of the method of the present invention the first treatment by an alkaline base of the efflux from the first sulfonation consists of a neutralization at ordinary temperature, and the second treatment consists of a neutralization at ordinary temperature, followed by a saponification under autogenous pressure at a temperature of between 100C and 300C.

The charge which comprises a mixture of sulfonatable hydrocarbons (olefin hydrocarbons and aromatic hydrocarbons) may also contain nonsulfonatable hydrocarbons such as paraffins and naphthenes. This is generally the case when the charge is prepared by dehydrogenation of normal paraffins.

When it is desired to prepare biodegradable detergents, it is necessary that a majority of the aromatic hydrocarbons subjected to the sulfonation composed of alkyl benzenes whose alkyl radicals are strictly linear and have carbon atoms numbering between 14 and 24 and on the other hand that the olefin hydrocarbons of the charge to be treated is composed primarily of 01- and/or internal straight-chain mono-olefins having carbon atoms numbering between 14 and 24.

In order to submit the charge to a first sulfonation, one can, for instance, feed diluted, gaseous sulfuric anhydride (sulfur'trioxide) at a temperature of between 10C and 40C into a gas which does not react with the products present in the reaction enclosure (nitrogen or air can be used). The amount of sulfur trioxide used should be such that there is a deficiency thereof with respect to the sulfonatable hydrocarbons: a ratio of the number of sulfur trioxide molecules to the number of sulfonatable hydrocarbon molecules of between 0.60 and 0.99, and preferably close to 0.8 for example is suitable. However, it is advantageous to operate under conditions such that the sulfur trioxide is in excess with respect to the quantity of olefin hydrocarbons present: a ratio of the number of sulfur trioxide molecules to the number of olefin molecules of between 1.0 and" 1.5, and preferably between 1.0 and 1.2 for example is suitable; thus the major part of the olefins is sulfonated, while only a small part of the aromatic hydrocarbons is. As a matter of fact, the applicant has observed that the alkyl aromatic hydrocarbons are less reactive than the olefin hydrocarbons having the same number of carbon atoms.

The efflux from the first sulfonation is subjected to neutralization (hereinafter called the first neutralization) at room temperature by an alkaline base; for instance caustic soda, when it is desired to prepare sodium sulfonates. I

In accordance with the first specific embodiment of the invention, the first neutralization is followed by a saponification (hereinafter called the first saponification) by an excess of base (for instance, caustic soda) under autogenous pressure at a temperature of between 100C and 300C. The saponification can be effected either on the organic phase alone, after separation by settling, or on the mixture of phases obtained after the neutralization. The purpose of this saponification is to transform the sultones into sulfonates. The saponification efflux is separated into an aqueous phase and into an organic phase which is subjected to a second sulfonation. For this purpose use can be made of gaseous sulfur trioxide diluted in an inert gas at ordinary temperature, the amount of sulfur trioxide used being in excess with respect to the residual sulfonatable hydrocarbons. A ratio of the number of sulfur trioxide molecules to the number of sulfonatable hydrocarbon molecules of between 1.0 and 1.50, and preferably between 1.10 and 1.40 is, for example, suitable. The efflux from the second sulfonation is subjected to a neutralization (hereinafter called the second neutralization) at ordinary temperature by an alkaline base (for instance, caustic soda) and then to asaponification under pressure (hereinafter referred to as the second saponification) under conditions similar to those of the first neutralization and of the first saponification. The second s'aponification can be effected either on the organic phase alone, after separation by settling, or on the'mixture ofvphases coming from the second neutralization. The efflux from the second saponification is separated into an organic phase, which for all practical purposes no longer contains sulfonatable hydrocarbons, and into an aqueous phase.

In accordance with the second specific embodiment of the invention, the efflux from the first neutralization is separated into an aqueous phase and into an organic phase. The organic phase is subjected to a second sulfonation, effected under conditions similar to the first, in the presence of a moderate excess of sulfur trioxide with respect to the residual sulfonatable hydrocarbons; a ratio of the number of sulfur trioxide molecules to the number'of sulfonatable hydrocarbon molecules of between 1.0 and 1.4, for example, is suitable. The absence of saponification prior to the second sulfonation results inthe presence of sultones in the organic phase treated in the second sulfonation. These sultones can combine with a sulfur trioxide molecule and give rise subsequently to secondary products such as sulfuric acid. This is why it is advantageous in this second embodiment to give the ratio of the number of sulfur trioxide molecules to the number ofsulfonatable hydrocarbon molecules a value which is as close as possible to 1.0. The value of this ratio must be compatible, however,.with a good conversion of the sulfonatable hydrocarbons. The efilux from the second sulfonation is subjected to a neutralization (second neutralization) by an alkaline base at ordinary temperature. The organic formed of the entire efflux from the second neutralization (organic phase plus aqueous phase) and of the aqueous phase coming from the first neutralization.

Each of the aqueous phases obtained after neutralization and/or saponification in either of the specific embodiments of the invention contains sulfonates. Detergents can therefore be prepared from each of these phases or their mixtures. The detergents prepared from the aqueous phases coming from the first sulfonation are richer in olefin sulfonates than those prepared from the aqueous phases coming from the second sulfonation. This property makes it possible to obtain detergents of given compositions which are enriched to a greater or lesser extent in olefin sulfonates (hydroxy alkyl sulfonates and alkenyl sulfonates) or orthodialkyl benzene sulfonates.

- The aqueous phases, taken individually or in mixture (and in particular those which come from the neutralizations), can be treated with a slightly alkaline solution at a temperature of between C and 300C to improve the final color of the detergents prepared from them. Such a treatment can be carried out in thepresence of a hydrocarbon which need not necessarily be the one from which the sulfonation charge'was prepared. I

One particularly advantageous application of the process of the invention resides in the sulfonation in two steps of a charge obtained by passing a fraction of normal paraffins having a number of carbon atoms of between 14 and 24 over a cyclizing, non-isomerizing, dehydrogenation catalyst consisting, for instance, of chromium oxide and potassium oxide which have been deposited on alumina or of platinum, lithium and arsenic deposited on alumina. The charge subjected to the first sulfonation on the one hand then consists of nonsulfonatable products which serve as diluents and which are primarily unconverted normal paraffins and a small quantity of naphthenes, and on the other band also consists of sulfonatable products which are olefin hydrocarbons, primarily linear mono-olefins, and aromatic hydrocarbons, primarily ortho-dialkyl benzenes (the alkyl radicals of which are linear).

In this specification and the accompanying drawings we have shown anddescribed a preferred embodiment of our invention and have suggested various alternatives and modifications thereof; but it is to be understood that many other changes and modifications can be made within the scope of the invention. These suggestions herein disclosed are selected and included for purposes of illustration, in order that others skilled in the art will be able more fully to understand the invention and principles thereof and will thus be enabled to modify it and embody it in a variety of forms, each as may be best suited to the conditions of a particular use.

Thetwo figures accompanying the specifications are diagrams illustrative of a preferred embodiment of the process of the invention as applied to the obtaining of sodium sulfonates.

FIG. 1 relatesto the first specific embodiment of the process of the invention;

FIG. 2 relates to the second specific embodiment.

Referring first to FIG. 1, a charge of hydrocarbons with carbon atoms numbering between 16 and 21, comprises on the one hand aromatic and olefin hydrocarbons (formed primarily of ortho-dialkyl benzenes, the alkyl radicals of which are linear,-and of straightchain mono-olefins) and on the other hand paraffins and small quantities of naphthenes, and is introduced via the line 1 into the first sulfonation reactor 2. One percent by weight gaseous sulfur trioxide in nitrogen is introduced into the reactor via the line 3, the gas escaping from this reactor via the line 4.

The efflux from the first sulfonation enters a first neutralization reactor 5. 4 N caustic soda in excess is introduced into the reactor 5 via the line 6. The first distillation efflux is saponified under autogenous pressure, at a temperature of 160C, in the first saponification reactor 7. A separating device 8 makes it possible to isolate an organic phase which is introduced via the line 9 into the reactor 10 in which it is subjected to a second sulfonation. Sulfur trioxide diluted in nitrogen is introduced into the reactor 10 via the line 11 with the gas escaping from said reactor via the line 12. The efflux of the second sulfonation is introduced into the second neutralization reactor 14. 4 N caustic soda in excess is introduced into said reactor via the line 15. The second neutralization efflux is saponified under pressure at a temperature of between 150C and 260C in a second saponification reactor 16. A separator 17 makes it possible to isolate and discharge through the line 18 an organic phase which contains the paraffins and the small quantities of naphthenes which were present in the initial charge, as well as small amounts of residual unsaturated derivatives.

The aqueous phase collected in the separator 17 as well as the aqueous phase collected in the separator 8 are conducted via the lines 19 and 20 respectively into an enclosure 21 where they are simultaneously subjected to de-oiling. The solvent is introduced into the enclosure 21 via the line 22. A separator 23 makes it possible to isolate an organic phase, which is introduced via a line 24 into a column 25, where it is subjected to distillation so as to separate the oil at 26 and In the second specifically described embodiment of the process of the invention which is illustrated in FIG. 2, the initial and final parts are identical to those of the first embodiment. The similar parts of FIGS. 1 and 2 have therefore been designated with the same reference numbers in the drawings. The efflux from the first neutralization is introduced into a separator 31 from which there is extracted an organic phase which is introduced at 32 into a second sulfonation reactor 33. Sulfur trioxide diluted in nitrogen enters said reactor through the line 34. The gases escape from the reactor via the line 35. After sulfonation, the mixture enters a second neutralization reactor 36 into which 4 N caustic soda in excess is introduced via the'line 37. The efflux from the second neutralization reactor as well as the aqueous phase collected at 38 in the separator 31 are subjected in the reactor 39 to an alkaline saponification under pressure at a temperature of between 150C and 260C. The efflux of the saponification is introduced into a separator 40 from which an organic phase is removed at-41 and an aqueous phase at 42. The organic phase 41 is formedof the paraffins and the traces of naphthenes which were present in the initial charge as well as of small quantities of residual unsaturated derivatives. The aqueous phase is subjected to de-oiling in the enclosure 21. The rest of the treatment is the same as that which was described with reference to FIG. 1.

The invention is further illustrated by the following illustrative examples.

EXAMPLE I This example does not fall within the scope of the invention. It is given to describe one method of obtaining a sulfonatable charge and by way of comparison in order to describe a single-stage sulfonation process.

1. PREPARATION OF A SULFONATION CHARGE A mixture of normal hexadecane and hydrogen is passed into a reactor at a temperature of 420C (the hour space velocity of the liquid normal hexadecane being equal to 1 and the hydrogen/normal hexadecane molar ratio being equal to 5). The reactor contains a cyclizing, non-iso'merizing, dehydrogenation catalyst. This catalyst consists of platinum, lithium, and arsenic deposited on alumina. The amounts of platinum, lithium and arsenic are equal to 0.75 percent, 0.50; and 0.36 percent respectively of the total'weight of the catalyst. The sulfonation charge thus prepared contains 10.4 mol% olefin hydrocarbons (about 82 percent of which are straight-chain mono-olefins) and 4.4 percent aromatic hydrocarbons (of which about percent are ortho-dialkyl benzenes having linear alkyl radicals). The rest of the charge consists of unreacted hexadecane and of traces of naphthenes. 2. PROCESS OF SULFONATION IN A SINGLE STAGE The charge prepared in this manner is subjected to sulfonation at 22C by gaseous sulfur trioxide diluted to a concentration of 1 percent in nitrogen for a period of 75 minutes. The theoretical molar ratio of sulfur trioxide consumed by the sulfonatable hydrocarbons is about 1.5. The efflux of the sulfonation is neutralized by 4 N caustic soda. The organic phase obtained is treated at 250C in an excess of caustic soda in an autoclave for 1 hour. After settling of the mixture, there is obtained a new aqueous phase which, after having been brought back to a neutral pH, is added to the first. For mols of sulfonatable hydrocarbons there were formed 91.0 mols of sodium sulfonate and 61.6 mols of sodium sulfate. The experimental molar ratio of sulfur trioxide combined with the sulfonatable hydrocarbons is equal to 1.52. The residual unsaturated products represent less than 1 mol% of the hydrocarbon phase.

The color, determined in accordance with ASTM D 1500, for a solution of 15 g of active matter per liter is equal to 6.5. v

The aqueous solution of detergent was subjected to decoloration by sodium hypochlorite at a temperature of 100C for 1 hour. The amount of hypochlorite consumed is 50 mols per 100 mols of sulfonate.

The color measured after decoloration under the same conditions as above is equal to 3.5.

EXAMPLES 11 AND III These examples relate to the first specific embodi-v ment of the process forming the object of the invention;

tion at a temperature of 22C by means of gaseous sulfur trioxide diluted to a proportion of 1 percent in nitrogen. The molar ratio of sulfur trioxide consumed to olefin hydrocarbons is equal to 1.0. The efflux of the sulfonation is then subjected to a first neutralization at room temperature by means of 4 N caustic soda in excess and then to a first saponification in an autoclave at a temperature of l60C. for 1 hour.

After separation of the organic phase, said phase is subjected to a second sulfonation, also carried out at a temperature of 22C., but for a-period of 30 minutes and with an excess of sulfur trioxide with respect to the sulfonatable hydrocarbons present, said excess being 30% by weight. The efilux is then subjected to a neutralization (second neutralization). The organic phase coming from said neutralization, after settling, is sub- .jected to a saponification (second saponification) in caustic soda at 250C. After settling, a new organic phase and a new aqueous phase are obtained. The mixture of all the aqueous phases constitutes, in this example, the detergent.

The results of the tests are set forth in Table I below. They are marked [1, and 11, for the first and second sulfonations respectively. The column 11 corresponds to the overall total. a I

Example I11 relates'to other tests which were carried out under conditions similar to those of Example 11. The results of these tests are also indicated in Table 1. Test 111; is identical to Test I I, Test I11 differs from Test i l only in the molar ratio of sulfur trioxide consumed to the remaining sulfonatable hydrocarbons, the

excess of sulfur trioxide used now being only 10 per- The A S TM color of the aqueous solutions containing the total quantity of the sulfonates, measured under the conditions described in Example 1, is equal to 3.5.

EXAMPLE IV This example also relates to the first specific embodiment of the process of the invention.

A mixture of paraffin hydrocarbons having a number of carbon atoms of between 16 and 21 is subjected to a cyclizing non-isomerizing, dehydrogenation under conditions identical to those described in Example 1.

After separation of the hydrogen and of the cracking products, the sulfonation charge has the following composition, expressed in mols:

1.4.2 percent olefin hydrocarbons, 75 percent of which are linear mono-olefins.

7.0 percent aromatic hydrocarbons, 75 percent of which are orthodialkyl benzenes having radicals.

The first and second sulfonations are carried out at 25C. with sulfur trioxide diluted to 1% in nitrogen. The reaction times are'70 and 60 minutes respectively. The molar ratio of sulfur trioxide used to olefin hydrocarbons present is equal to 1.2 in the first sulfonation. Upon the second sulfonation, the molar ratio of sulfur trioxide used to sulfonatable hydrocarbons is equal to 1.3 and corresponds therefor to an excess of 30 percent sulfur trioxide. The results obtained in these tests have been entered in Table 11 below. The AST M color of the aqueous solution containing the total amount of thefso dium sulfonates, measured cent. under the conditions described in Example 1, is 3.5.

TABLE 1 EXAMPLE 11 ill TEST 11,- ll 11', 111 111 111 -SULFONAT1ON- Time (Minutes) 30 60 30 90 Theoretical I molar ratio SOJolefins E 1.0 SO /remaining SO /olefins=1.0 SO /remaining I sufonatable sulfonatable hydrocarbons=1.3 hydrocarbons E 1.1

Temperature ("C) 22 22 22 22 Composition of the charge (mol% of the charge) in I -01efins 10.4 2.9 10.4 10.4 2.9 10.4 -Aromatics 4.4 3.2 4.4 4.4 g 3.2 4.4

AFTER SAPONIFI- CATIQN Composition of the hydrocarbon phase (molil )in 0 1efins 2.9 0.4 0.4 2.9 0.4 0.4 -Aromatics 3.2 0.2 0.2 3.2 0.8 0.8

Composition of the aqueous phase (mo17r sulfonalable hydrocarbons used) in -NaRSO 55 89.9 89.4 55 78.5 85.0 Na,SO 3 14.5 44.0 31.8 14.5 36.6 29.0

Experimental molar 0.69 1.34 1.21 0.69 1.15 1.14

ratio; SO; combined/sulfonatable hydrocarbons linear alkyl- TABLE 11 EXAMPLE 1V TEST W, W, IV

-SULFONAT1ON Time (minutes) 70 60 130 Theoretical Molar Ratio SO /Olefins E 1.2 So /sulfonatable hydrocarbons 1.3

Temperature (C) 25 25 Composition of the Charge (mol7n of the Charge) in -Olefins 14.2 1.8 14.2 -Aromatics 7.0 5.6 7.()

AFTER SAPONlFlCATlON Composition of the Hydrocarbon phase (mol7r) in -Olefins 1.8 0.6 0.6 -Aromatics 5.6 0.8 0.8

Composition of the Aqueous Phase (mol7r of sulfonatable Hydrocarbons used in NaRSO 68.6 99.4 98.5 Na SO 3 11.0 26.9 19.1

Experimental Molar Ratio S 0.8 1.26 1.18 Combined/sulfonatable Hydrocarbons i EX PLFV 5 asavirig in sulfonatirig reagent, since the excess thereof This example concerns the second specific embodiment of the process of the invention.

An initial charge obtained by the method described in Example 1 is subjected to a first sulfonation at 22C. with gaseous sulfur trioxide diluted to 1 percent in nitrogen. The molar ratio of sulfur trioxide used to olefin hydrocarbons is close to 1.2. The efflux of the sulfonation is subjected to a first, neutralization at room tem-. perature by means of 4 N caustic soda and is tlienpa 40 rated into an aqueous phase and an organic phase. Theorganic phase is subjected to a second sulfonation by means of sulfur trioxide diluted to 1 percent in nitrogen. An excess (20 percent) of sulfur trioxide with respect to the residual sulfonatable hydrocarbons is used. The efflux of the second sulfonation is subjected to a neutralization by 4 N caustic soda at room temperature. The efilux of this neutralization, as well as the aqueous phase coming from the first neutralization, are treated with caustic soda at 250C. in an autoclave for 1 hour.

The sum total for 100 mols of sulfonatable hydrocarbons used initially is as follows:

NaRSO 94.9

Na SO 31.4

The experimental molar ratio of sulfur trioxide combined with sulfonatable hydrocarbons is equal to 1.26. The ASTM color of the aqueoussolution, measured under the conditions described in Example 1, is equal 60 to 1.5.

The process of the invention makes it possible to sulfonate a mixture of olefin and aromatic hydrocarbons under the best possible conditions. Its application to hydrocarbons having a number of carbon atomsof be- 65 tween 14 and 24 results in biodegradable detergents under particularly advantageous conditions. As a inatter of fact. it makes it possible simultaneously to effect with respect to the sulfonatable hydrocarbons is reduced and at the same time it decreases the production of sodium sulfate. Moreover, the sulfonates obtained are of light color and do not require further decoloring.

I claim:

1. In a process for the sulfonation of a feed comprising a mixture of sulfonatable hydrocarbons comprising dialkylbenzenes whose alkyl radicals are linear and the number of carbon atoms of which is between 14 and 24 and of linear olefin hydrocarbons, the number of carbon atoms of which is between 14 and 24, the improvement which comprises two stage sulfonation by thefollowing steps in succession:

a. a first sulfonation of said feed at a temperature between 10 and 40C by sulfur trioxide diluted in an inert gas effected in the presence of a molar deficiency of sulfur trioxide with respect to the sulfonatable hydrocarbons, the molar ratio of the amount of sulfur trioxide used and of sulfonatable hydrocarbons present being between about 0.60 and 0.99;

b. a first neutralizationtreatment by an alkaline base of the efflux from the first sulfonation yielding an organic phase and an aqueous phase;

0. a first saponification treatment by and alkaline base of either the organic phase or the mixture of organic and aqueous phases from step (b) and in turn yielding a new. organic phase and aqueousphase;

d. a second sulfonation effected on the organic phase coming from the first saponification treatment by an alkaline base, the said second'sulfonation being carried out at a temperature between 10 and 40C by sulfur trioxide diluted in an inert gas in thepresence of an excess of said sulfur trioxide with respect to the sulfonatable hydrocarbons present, the molar ratio of the sulfur trioxide used to the sulfol l natable hydrocarbons present being between 1.0 and 1.5;

e. a second neutralization treatment by an alkaline base of the efflux from the second sulfonation yielding a further organic phase and aqueous phase; and

f. a second saponification treatment by an alkaline base of either the organic phase or the mixture of organic and aqueous phases from step (e),

2. A process as recited in claim 1 wherein the said first and second saponification treatments are performed on the mixtures of aqueous and organic phases formed in the neutralization steps of (b) and (e).

3. A process as recited in claim 1 wherein the organic phase and aqueous phase formed in the said first neutralization treatment (b) are separated and the organic phase only is subjected to saponification and further wherein the organic phase and aqueous phase formed in said second neutralization treatment (e) are subjected to said second saponification treatment without prior separation.

4. A process as recited in claim 1 wherein the organic phase and aqueous phase formed in each of said first and second neutralization treatments (b) and (e) respectively are separated from one another respectively and only the organic phases from said first and second neutralization treatments are subjected to saponification.

5. A process as recited in claim 1 wherein the organic phase and aqueous phase formed in said first neutralization treatment (b) are saponified without prior separation and the aqueous and organic phases formed in said second neutralization treatment (e) are separated and only the organic phase thereafter subjected to saponification.

6. A process as recited in claim 1 wherein the ratio in step (a) is about 0.8 and the ratio in step (e) is be tween 1.10 and 1.40.

7. In a process for the sulfonation of a feed comprising a mixture of sulfonatable hydrocarbons comprising dialkylbenzenes whose alkyl radicals are linear and the number of carbon atoms of which is between 14 and 24 and of linear olefin hydrocarbons, the number of carbon atoms of which is between 14 and 24, the improvement which comprises two stage sulfonation by the following steps in succession:

a. a first sulfonation of said feed at a temperature between l and 40C by sulfur trioxide diluted in an inert gas effected in the presence of a molar deficiency of sulfur trioxide with respect to the sulfonatable hydrocarbons, the molar ratio of the amount of sulfur trioxide used and of sulfonatable hydrocarbons present being between about 0.60 and 0.99;

b. a first neutralization treatment by an alkaline base of the efflux from the first sulfonation yielding an organic phase and an aqueous phase;

c. a second sulfonation effected on the organic phase coming from said first neutralization treatment (b), the said second sulfonation being carried out at a temperature between 10 and 40C by sulfur trioxide diluted in an inert gas in the presence of an excess of said sulfur trioxide with respect to the sulfonatable hydrocarbons present, the molar ratioof the sulfur trioxide used to the sulfonatable hydrocarbons present being between 1.0 and 1.4;

d. a second neutralization treatment by an alkaline base of the efflux from the second sulfonation yielding a further organic phase and aqueous phase;

e. a saponification treatment by an alkaline base of either the organic phase or the mixture of organic and aqueous phases from step (d).

8. A process as recited in claim 7 wherein the organic and aqueous phases formed in said second neutralization treatment are saponified without prior separation from one another.

9. A process as recited in claim 7 wherein the aqueous phase formed in said first neutralization treatment (b) is combined with the organic and aqueous phases formed in said second neutralization treatment (d) and the combined stream is saponified.

10. A process as recited in claim 7 wherein the organic and aqueous phases formed in said second neutralization treatment (d) are separated from one another and the organic phase from said second neutralization treatment is combined with the aqueous phase from said first neutralization treatment (b) and that combined stream issaponified.

11. A process as recited in claim 7 wherein the ratio in step (a) is close to 0.8 and the ratio in step (d) is about 1.0.

12. A process as recited in claim 7 wherein in the first sulfonation step the molar ratio of sulfur trioxide to olefin hydrocarbon present is between 1.0 and 1.5. 

2. A process as recited in claim 1 wherein the said first and second saponification treatments are performed on the mixtures of aqueous and organic phases formed in the neutralization steps of (b) and (e).
 3. A process as recited in claim 1 wherein the organic phase and aqueous phase formed in the said first neutralization treatment (b) are separated and the organic phase only is subjected to saponification and further wherein the organic phase and aqueous phase formed in said second neutralization treatment (e) are subjected to said second saponification treatment without prior separation.
 4. A process as recited in claim 1 wherein the organic phase and aqueous phase formed in each of said first and second neutralization treatments (b) and (e) respectively are separated from one another respectively and only the organic phases from said first and second neutralization treatments are subjected to saponification.
 5. A process as recited in claim 1 wherein the organic phase and aqueous phase formed in said first neutralization treatment (b) are saponified without prior separation and the aqueous and organic phases formed in said second neutralization treatment (e) are separated and only the organic phase thereafter subjected to saponification.
 6. A process as recited in claim 1 wherein the ratio in step (a) is about 0.8 and the ratio in step (e) is between 1.10 and 1.40.
 7. In a process for the sulfonation of a feed comprising a mixture of sulfonatable hydrocarbons comprising dialkylbenzenes whose alkyl radicals are linear and the number of carbon atoms of which is between 14 and 24 and of linear olefin hydrocarbons, the number of carbon atoms of which is between 14 and 24, the improvement which comprises two stage sulfonation by the following steps in succession: a. a first sulfonation of said feed at a temperature between 10* and 40*C by sulfur trioxide diluted in an inert gas effected in the presence of a molar deficiency of sulfur trioxide with respect to the sulfonatable hydrocarbons, the molar ratio of the amount of sulfur trioxide used and of sulfonatable hydrocarbons present being between about 0.60 and 0.99; b. a first neutralization treatment by an alkaline base of the efflux from the first sulfonation yielding an organic phase and an aqueous phase; c. a second sulfonation effected on the organic phase coming from said first neutralization treatment (b), the said second sulfonation being carried out at a temperature between 10* and 40*C by sulfur trioxide diluted in an inert gas in the presence of an excess of said sulfur trioxide with respect to the sulfonatable hydrocarbons present, the molar ratio of the sulfur trioxide used to the sulfonatable hydrocarbons present being between 1.0 and 1.4; d. a second neutralization treatment by an alkaline base of the efflux from the second sulfonation yielding a further organic phase and aqueous phase; e. a saponification treatment by an alkaline base of either the organic phase or the mixture of organic and aqueous phases from step (d).
 8. A process as recited in claim 7 wherein the organic and aqueous phases formed in said second neutralization treatment are saponified without prior separation from one another.
 9. A process as recited in claim 7 wherein the aqueous phase formed in said first neutralization treatment (b) is combined with the organic and aqueous phases formed in said second neutralization treatment (d) and the combined stream is saponified.
 10. A proceSs as recited in claim 7 wherein the organic and aqueous phases formed in said second neutralization treatment (d) are separated from one another and the organic phase from said second neutralization treatment is combined with the aqueous phase from said first neutralization treatment (b) and that combined stream is saponified.
 11. A process as recited in claim 7 wherein the ratio in step (a) is close to 0.8 and the ratio in step (d) is about 1.0.
 12. A process as recited in claim 7 wherein in the first sulfonation step the molar ratio of sulfur trioxide to olefin hydrocarbon present is between 1.0 and 1.5. 